ORLANDO, Fla. -- A postal worker says a mysterious leaking package from Yemen has left him seriously ill, but the U.S. Postal Service denies the package ever existed.

The center tracked down co-workers who said that they saw and smelled the package and that Lill, now 44, acted to protect them. The missing package has created a mystery – and determining what was in it, if it existed, could be the key to curing Lill.

"I think they've just been protecting themselves," said George Chuzi, a Washington lawyer helping Lill and his family pressure USPS to investigate. "If we're right, they didn't do something they were supposed to do."

USPS denies that Lill was exposed to a potentially toxic package. Postal service officials declined comment when contacted by FCIR, but in a March 9 letter to Chuzi, USPS lawyer Isabel M. Robison acknowledged that a harmless spill had occurred on Feb. 2, 2011. But she said nothing was spilled on Feb. 4, 2011.

"A review of Postal Service records and multiple inquiries at both the Area and District levels has confirmed – as we previously indicated – that there was no hazardous spill on February 4, 2011 at the Orlando" mail processing center, she wrote.

But Lill and his co-workers Paz Oquendo and Yolanda Ocasio told a different story. Oquendo said she smelled the noxious odor first, which was coming from one of the large mailbags hanging near the package-conveyor belts.

She said she told Lill, the shift supervisor monitoring sorting from a platform.

Lill headed toward the center of the sorting floor – an area workers call "the belly" – to investigate.

Then he smelled it – a strong chemical stench that he said he couldn't identify. It was coming from a bag wet with a brown, viscous substance. Lill looked in the wet sack and saw a broken package with tubes and wires sticking out. He remembers reading the return address with surprise: Yemen. Four months earlier, two bombs from Yemen had been sent through FedEx and UPS in an unsuccessful al-Qaida attempt to blow up cargo planes, and the postal service had alerted its workers to be on the lookout for packages coming from the southern end of the Arabian Peninsula.

Fearing the package was hazardous, Lill ordered the 40 postal employees out of the belly and immediately opened the large bay doors for ventilation. Lill said he then moved the bag to a cart and pushed it outside to the hazmat shed.

Lill said he then radioed his manager to notify her of the suspicious spill. She told him the next on-duty supervisor would finish handling the incident. FCIR obtained a time-stamped email Lill sent to his supervisor, Cynthia Hickman, reporting the exposure to a potentially toxic substance. Hickman did not respond to requests for comment.

Lill said that after the moving the package, his throat burned and the fumes gave him a headache. He called his mother in Rochester, N.Y., in case it made the news.

But it didn't. The FCIR reported that the postal service did not investigate the suspicious package as a security or health threat and did not report it to the U.S. Department of Homeland Security as is the protocol.

In the weeks after Feb. 4, Lill, who had rarely missed a day during 10 years of working with the postal service, fell inexplicably ill. He sleeps 16 hours a day, cannot work and now must be cared for his by mother.

Today, after having seen more than two dozen doctors, including toxicologists and neurologists, no one has been able to diagnose his illness.

"He was so vital, so energetic and so personable," said his mother Janet Vieau, 64. "He would play basketball and the drums."

U.S. Rep. Ann Marie Buerkle, R-N.Y., wants answers. Buerkle, whose district includes Lill's new residence in Rochester, has pressured USPS to investigate.

"We want to see if the appropriate steps were taken by the post office, to see if the employees are safe," said Timothy Drumm, Buerkle's chief of staff." But since they say the incident did not happen, we can't even get that far."